TL;DR
  • Polish sp. z o.o. (LLC) is a popular vehicle for foreign founders — low capital requirement (5 000 zł), fast registration, full EU access.
  • Your Polish LLC has a Polish NIP, so KSeF is mandatory from Feb 1, 2026.
  • You don't need to speak Polish to issue invoices — pick a system with an English UI (Fakturium has one, Fakturownia partially).
  • Your accountant ("księgowa") receives JPK_FA exports monthly. You don't post journal entries yourself.
  • Common mistakes: missing NIP on invoice, wrong NBP exchange rate, issuing invoices outside KSeF.

Setting up a Polish sp. z o.o. (the equivalent of an LLC or Ltd) is one of the easiest ways for a foreign founder to get an EU-based legal entity. Registration takes 1-3 days through the s24 portal, minimum capital is 5 000 zł (~1 100 EUR), and you get full single-market access. But once you start invoicing, you hit the wall: KSeF, Polish-only government portals, and an accountant who speaks Polish at native speed. This article is a practical guide to what you actually need to do.

Step 1 — Understand the split with your accountant

In Poland, accounting work is usually outsourced to a księgowa (bookkeeper) or a biuro rachunkowe (accounting firm). They handle:

  • Monthly VAT returns (JPK_V7M) — submitted to the tax office on your behalf.
  • Monthly bookkeeping entries (KPiR for sole prop, full books for sp. z o.o.).
  • Annual corporate income tax return (CIT-8).
  • ZUS social-security declarations.

You handle:

  • Issuing invoices to your customers.
  • Sending invoices to KSeF (or using software that auto-sends).
  • Tracking payment status — was it paid, was it late, do I send a reminder?
  • Forwarding cost invoices to your accountant (rent, software subscriptions, contractors).

Fakturium covers the entire "you handle" list and ships JPK_FA exports your accountant can import in one click.

Step 2 — Setting up KSeF (do this ONCE)

KSeF requires authentication. There are three options for a sp. z o.o.:

  • Trusted Profile (Profil Zaufany) — the founder's personal identity, free to set up but you must be a Polish resident or have a bank account at a participating PL bank.
  • Qualified electronic signature — a paid cert (~200 PLN/year from Asseco or Sigillum). Works for any EU resident.
  • Authorization for a tax advisor or accountant — they sign in on your behalf with their own credentials.
Practical tip

If you're a foreign founder without a Polish bank account or PESEL, the qualified signature is the fastest path. Buy one from a Polish certification provider, install it on your laptop, register it in KSeF as the company's authorized representative.

Step 3 — Issue your first invoice

Fakturium's flow for a foreign founder:

  • Set your company data once (NIP, name, address, bank). It will pre-fill every invoice.
  • Add a customer by typing their NIP — Fakturium auto-fills name + address from the VIES + Polish business registry.
  • Add line items (description, qty, unit price, VAT rate). Choose currency — PLN, EUR, USD, GBP, all supported.
  • Click "Issue + send to KSeF". The system generates FA(3) XML, signs it, sends to the Ministry, receives the KSeF ID, generates the PDF, and emails the buyer.

Time spent: under 30 seconds for a recurring customer, ~1 minute for a new one.

Common mistakes (and how to avoid them)

Mistake #1 — Missing or wrong NIP

Polish invoices MUST show the seller's NIP. A US-style "EIN" or German "USt-IdNr" is not a substitute. Fakturium validates NIP format and checksum before letting you issue.

Mistake #2 — Wrong currency conversion

If you invoice in USD but the buyer is a Polish company, the VAT amount must also be shown in PLN — converted at NBP's USD/PLN reference rate from the day BEFORE the supply. Manually pulling rates from nbp.pl is error-prone. Use software that fetches them automatically.

Legal basis
Polish VAT Act, art. 31a §1
Sets the NBP day-before rule for foreign currency invoices.

Mistake #3 — Issuing the invoice outside KSeF

Some founders issue invoices in Word/Excel "to send later through KSeF". This is risky — if the invoice is dated before the KSeF submission and the tax office audits, they may treat the Word version as the primary invoice (with VAT due immediately) and reject the KSeF version as a duplicate.

Warning

KSeF is the legal source of truth. If you issue an invoice, send it to KSeF within 7 days (ideally immediately). Don't keep "draft invoices" in Word — start in software that emits FA(3) XML.

Mistake #4 — Forgetting to forward cost invoices

Every cost invoice you receive (Google Ads, AWS, your laptop from Allegro) needs to land with your accountant by the 5th of next month — otherwise you lose the input VAT deduction. Fakturium imports cost invoices via the KSeF API and forwards them to your accountant's inbox automatically.

Working with a Polish-only accountant

Most Polish bookkeepers speak some English but write entirely in Polish. To minimize friction:

  • Agree on a monthly checklist — what you send (cost invoices, payment confirmations), what they send back (JPK_V7M filing confirmation, monthly P&L).
  • Use software that exports JPK_FA in the standard format — your accountant imports it in 2 clicks instead of typing each invoice.
  • Have a quarterly 30-min call with a translator if your accountant speaks no English at all — for ad-hoc questions.

Costs to budget for

  • Bookkeeping: 350 - 1 200 zł / month depending on volume.
  • KSeF qualified signature: 200 zł / year (Sigillum, Asseco).
  • Invoicing software: 0 - 199 zł / month (Fakturium Free = 5 invoices, Pro = 99 zł unlimited).
  • Annual CIT return prep: 800 - 2 500 zł.
  • Optional: virtual office address: 100 - 300 zł / month.

Total fixed cost for a low-volume sp. z o.o. (under 20 invoices/month): ~5 000 - 10 000 zł / year. Reasonable for the EU entity benefit.

Bottom line

You don't need to speak Polish to run a sp. z o.o. compliantly. You need (a) an accountant who handles VAT/CIT filings, (b) software that handles invoicing + KSeF in English, (c) a discipline of forwarding cost invoices monthly. The rest is just normal business.